Muffler for aluminum cell tapping crucible

ABSTRACT

An apparatus for reducing the noise level of a stream of air exiting a tapping crucible in aluminum reduction operations. The air is used to create a vacuum in the tapping crucible, thereby promoting siphon removal of molten aluminum from the reduction cell. The apparatus of this invention, commonly referred to as a muffler, comprises an outer conduit having entrance and exit openings, an inner conduit centrally attached within said outer conduit, said inner conduit having an entrance opening, an exit opening enclosed with a cup welded to said inner conduit, and exhaust slots equally spaced around said inner conduit&#39;&#39;s circumference.

United States Patent 1 1 Benton et al. 51 May 15, 1973 [54] MUFFLER FOR ALUMINUM CELL 3,491,849 1/1970 Newkirk ..181/72 TAPPING CRUCIBLE 3,561,561 2 1971 Trainor ..181/72 [75] Inventors: Charles Michael Benton; Howard E. FOREIGN PATENTS ()R APPLICATIONS Niehaus, both of Owensboro, Ky.

1,094,694 12/1954 France ..l81/40 [73] Assignee: National-Southwire Aluminum Com- 1,294,393 5/1969 Germany ....l81/56 pany, Carrollton, Ga. 771,759 4/1957 Great Britain. ....181/57 475,047 10/1952 ltal ..l8l 56 [221 Flledi P 1971 303,581 1 1929 ore at Britain 181/67 N0: 379,836 8/1964 Switzerland ..l8l/72 Primary Examiner-Richard B. Wilkinson [1.8. CI. R, Assistant Examiner-John Gonzales [51] Int. Cl ..F0ln l/l0 Attorney-Van et al [58] Field of Search ..181/35 C, 47 R, 46,

181/40, 50, 56, 57, 53, 60, 63, 67, 72, 35 A, [57] ABSTRACT An apparatus for'reducmg the noise level of a stream [56] References Cited of air exiting a tapping crucible in aluminum reduction operations. The air is used to create a vacuum in the UNITED STATES PATENTS tapping crucible, thereby promoting siphon removal of molten aluminum from the reduction cell. The apfigg: paratus of this invention, commonly referred to as a 728200 5/1903 181/53 muffler, comprises an outer condult having entrance 19153698 H1912 Maxim 181/50 and exit openings, an inner conduit centrally attached 1,747,014 2/1930 Kersey -181/63 within said outer conduit, said inner conduit having an 2 0 7 1 937 Gray 131 47 R entrance opening, an exit opening enclosed with a cup 2,089,492 8/1937 Lambert... ..181/42 welded to said inner conduit, and exhaust slots equally 7 6/l950 MflrX A spaced around said inner conduits circumference. 3,454,129 7/1969 Everett ..l81/57 7 Claims, 3 Drawing Figures PATENTEDIJAY 1 51m 3'. 7:32 948 I NVENTOR. CHAEL 5 M/CH/IZL BEA/mu MUFFLER FOR ALUMINUM CELL TAPPING CRUCIBLE SUMMARY OF THE INVENTION This invention relates to an apparatus used to reduce the noise level of a stream of air, and more particularly to reduce the noise level of a stream of air exiting from a tapping crucible used in aluminum reduction operations.

In aluminum production molten aluminum is formed in a reduction cell. The aluminum produced settles to the lower portion of the cell, which usually lies below floor level. In this process, the molten aluminum is removed from the base of the reduction cell by suction. An apparatus commonly referred to as a siphon spout is used in the suction collection of newly separated molten aluminum. The siphon spout is attached to a large container or collection pot, herein referred to as a crucible. High pressure air is used to create a partial vacuum in the crucible and siphon spout. The air travels through the straight legs of a T shaped valve located on the crucible lid, creating a partial vacuum in the right angle leg which has an opening into the crucible. The air exits the exhaust end of the T valve, hereinafter referred to as the exhaust pipe. The high pressure air used to create a partial vacuum in the crucible requires a noise reducer, hereinafter referred to as a muffler, which usually is attached at a point where air exhausts from the straight leg (exhaust pipe) of the T shaped valve.

Prior art noise reducers generally have been commercially available diesel truck mufflers or mufflers of similar design. These mufflers have many disadvantages which are overcome by the present invention, such as; excessive cost, large size which causes difficulty in handling and which necessitates removal from the crucible after each tapping operation, the interior frequently becomes stopped with small aluminum particles and the muffler must be cleaned or replaced, and excessive wear of muffler interior materials which necessitates frequent replacement.

One object of this invention is to provide an apparatus which reduces the noise level of air exiting a tapping crucible during tapping of molten aluminum.

Another object of this invention is to provide an apparatus used for noise reduction which is reliable and durable near intense heat and molten metal.

Other objects and advantages of this invention will become apparent after reading the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectioned side elevation view of the muffler.

FIG. 2 is an end view of the muffler showing the angle of the grooves located in the inner conduit of the muffler.

FIG. 3 is a side view showing the muffler attached to a crucible.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a reducer, 11, is connected to the exit end of the exhaust pipe. One end of a bell reducer, 12, is connected to reducer 11. The other end of hell reducer 12 is connected to bushing 13. The threads of bushing 13 are used to connect conduit 14 to bell reducer 12. Conduit 14 can be a constant diameter collar or a bell reducer. Conduit 15 directs the air flow and is attached at the center of bushing 13. The conduit 15 has a metal cap, 16, attached to its end, preferrably by welding, with a layer of absorbant material, 17, glued to the inside of the cap. Absorbant material 17 preferrably is composed of asbestos cloth or foam rubber. Advantageously the thickness of the absorbant material is approximately one-tenth inch for asbestos cloth and approximately one-half inch for foam rubber. Suitable glue is any commercially available glue which will bond cloth or rubber to metal and retain an effective bond at high temperatures. Preferrably Elrners glue manufactured by Bordens, Inc. is used. Conduit 15 is encircled by rectangular grooves, 18, sometimes hereinafter referred to as exhaust slots, which allow air to escape. The rectangular grooves, 18, are equally spaced around the circumference of conduit 15. These grooves are cut in such a manner that they begin on the inner wall of the conduit at a more narrow width than the groove opening on the outside wall of the conduit. A 30 degree slant of thickness of the grooves from the inner wall to the outer wall of the conduit causes air flow to be dispersed more evenly onto an absorbent material, 19, on the interior walls of the muffler.

The walls of the main body, 20, of the muffler are attached by threads to conduit 14. These walls comprise a conduit with an open end. Absorbent material 19, glued to the inner walls of conduit 20, absorbs some of the exiting airs energy and transfers some to the walls of the muffler, thereby greatly lessening the decible rating and lowering the pitch of sound emitted during tapping operations. Coating 19 preferrably is composed of asbestos cloth or foam rubber. Advantageously the thickness of the coating is approximately one-tenth inch for asbestos cloth and onehalf inch for foam rubber. Suitable glue is any commerically available glue which will bond cloth or rubber to metal and retain an effective bond at high temperatures. Preferrably Elmers glue manufactured by Bordens, Inc. is used.

Advantageously the muffler of the present invention has an overall length of approximately 14 inches and can easily and quickly be attached to the crucible exhaust pipe by one person. The exhaust pipe for air exiting the crucible-siphon apparatus generally is about 2 l/2 inches in diameter. Reducer 11 increases the size of the opening diameter from 2 U2 inches to 3 inches. Bell reducer 12 further increases the opening diameter from 3 inches to from 4 to 5 inches (a range of diameter increase of from 33 to 67 percent). Bushing 13 centers conduit 15 within conduits 14 and 20, and reduces the opening diameter from 4 to 5 inches to 2 to 2 l/2 inches, (range of diameter reduction of from 40 to 62.5 percent). Advantageously conduit 14, attached to bushing 13, is a collar of constant diameter of 4 to 5 inches or is a bell reducer which increases the opening diameter from 4 inches to not more than 5 inches (an increase of up to 20 percent). Conduit 14 is attached to conduit 20 which has a diameter equal to the diameter of conduit 14, i.e., from 4 to 5 inches.

Preferrably conduit 15 is about 6 inches in length, approximately 43 percent the preferred exterior length of the muffler. Rectangular grooves 18 are approximately 3 inches in length, about 50 percent the length of con duit 15, and located midway between the ends of conduit 15, i.e, 1 1/2 inches from either end. Grooves 18 are equally spaced around the diameter of conduit 15 and have a /16 inch space between the grooves on the interior wall. The grooves are flared out at a 30 degree slant from the interior wall to the exterior wall of conduit l5, facilitating a more even air flow from conduit 15. The air flow which begins at the exhaust pipe on the crucible lid and travels toward the conduit walls of the muffler is substantially quieted as its passes from the muffler.

Referring to FIG. 3, muffler 21 is attached to crucible 24 by a T shaped valve, 22. During the siphon operation air hose 23 is connected to valve 22. High pressure air passes from hose 23 through valve 22 and exits muffler 21, thereby creating a vacuum or reduced pressure in crucible 24 and siphon spout 25.

The muffler of this invention does not need to be removed after each tapping operation as prior art mufflers do. The cost of manufacturing a muffler of the present invention is approximately one-fifth that of prior art mufflers, and prior art mufflers have a useful life markedly lower than the present invention. Aluminum particles do not readily collect in the muffler of this invention, and the particles which do collect are readily expelled simply by removing the muffler from the exhaust pipe of the crucible and rapping it against the crucible or a similar stationary object.

The efficiency of the present invention is superior to prior art mufflers in that it reduces the speed of air entering to approximately one-half upon exiting, reduces the decible level from approximately 115 upon entering to approximately 90 upon exiting, and lowers the pitch of sound produced to reduce or eliminate the more piercing sounds.

While this invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

What is claimed is:

1. An apparatus for reducing the noise level of a stream of air exiting a tapping crucible in aluminum reduction operations, said stream of air creating a vacuum in the tapping crucible, said vacuum being means for siphon removal of molten aluminum from the reduction cell, said apparatus comprising an outer conduit having an entrance opening and an inner conduit centrally situated within said outer conduit, said inner conduit having an entrance opening, an exit opening enclosed by a cap affixed to said inner conduit, elongated exhaust slots equally spaced around said inner conduits circumference, said elongated exhaust slots extending over approximately one-half the length of said inner conduit.

2. The apparatus of claim 1 wherein the outer conduit has energy absorbing material affixed to its interior walls and the inner conduit has energy absorbing material affixed to the interior of its cap.

3. The apparatus of claim 2 wherein the energy absorbing material is selected from the group consisting of asbestos cloth and foam rubber.

4. The apparatus of claim 1 wherein the inner conduit has a length equal to at least 40 percent of the exterior length of the apparatus.

5. The apparatus of claim 1 wherein said exhaust slots diverge radially outwardly whereby air emitting therefrom will be dispersed to impinge evenly over substantially the entire inner annular surface of said outer conduit extending the length of said slots.

6. The apparatus of claim 5 wherein said exhaust slots diverge at an angle of approximately 30 degrees.

7. Apparatus for receiving molten aluminum from an aluminum reduction cell, said apparatus comprising a crucible, a siphon spout connecting said crucible and said reduction cell, a lid disposed on said crucible having a T-shaped valve connected thereto and extending into the interior of said crucible, a source of compressed air, means for passing compressed air from said source through one end of said T-shaped valve for creating a vacuum in said crucible, a bell reducer connected to other end of said T-shaped valve for receiving compressed air therethrough, a bushing disposed in said bell reducer, a cylinder having one end extending from said bushing and communicating with the interior of said bell reducer, the other end of said cylinder being closed, a tubular conduit surrounding said cylinder and defining an annular chamber thereabout, said conduit communicating at one end with the atmosphere, and elongated exhaust slots extending over a substantial portion of said cylinder communicating the interior thereof with said annular chamber. 

1. An apparatus for reducing the noise level of a stream of air exiting a tapping crucible in aluminum reduction operations, said stream of air creating a vacuum in the tapping crucible, said vacuum being means for siphon removal of molten aluminum from the reduction cell, said apparatus comprising an outer conduit having an entrance opening and an inner conduit centrally situated within said outer conduit, said inner conduit having an entrance opening, an exit opening enclosed by a cap affixed to said inner conduit, elongated exhaust slots equally spaced around said inner conduit''s circumference, said elongated exhaust slots extending over approximately one-half the length of said inner conduit.
 2. The apparatus of claim 1 wherein the outer conduit has energy absorbing material affixed to its interior walls and the inner conduit has energy absorbing material affixed to the interior of its cap.
 3. The apparatus of claim 2 wherein the energy absorbing material is selected from the group consisting of asbestos cloth and foam rubber.
 4. The apparatus of claim 1 wherein the inner conduit has a length equal to at least 40 percent of the exterior length of the apparatus.
 5. The apparatus of claim 1 wherein said exhaust slots diverge radially outwardly whereby air emitting therefrom will be dispersed to impinge evenly over substantially the entire inner annular surface of said outer conduit extending the length of said slots.
 6. The apparaTus of claim 5 wherein said exhaust slots diverge at an angle of approximately 30 degrees.
 7. Apparatus for receiving molten aluminum from an aluminum reduction cell, said apparatus comprising a crucible, a siphon spout connecting said crucible and said reduction cell, a lid disposed on said crucible having a T-shaped valve connected thereto and extending into the interior of said crucible, a source of compressed air, means for passing compressed air from said source through one end of said T-shaped valve for creating a vacuum in said crucible, a bell reducer connected to other end of said T-shaped valve for receiving compressed air therethrough, a bushing disposed in said bell reducer, a cylinder having one end extending from said bushing and communicating with the interior of said bell reducer, the other end of said cylinder being closed, a tubular conduit surrounding said cylinder and defining an annular chamber thereabout, said conduit communicating at one end with the atmosphere, and elongated exhaust slots extending over a substantial portion of said cylinder communicating the interior thereof with said annular chamber. 